The present inventive subject matter relates generally to the art of xerography. Particular but not exclusive relevance is found in connection with xerographic print engines, e.g., such as found in printers, copiers, facsimile machines, multi-function printers, etc. The present specification accordingly makes specific reference thereto at times. However, it is to be appreciated that aspects of the present inventive subject matter are also equally amenable to other like applications and/or environments.
A xerographic print engine generally includes a photoreceptor or photosensor, e.g., in the form of a rotating cylindrical drum or belt or otherwise. In some xerographic print engines, a row or bar of light emitting diodes (LEDs), also known as an LED print head, is used to selectively illuminate a surface of the photoreceptor with light to produce and/or define a latent image thereon. The latent image may then be transferred from the photoreceptor to a sheet of paper or other image receiving medium, e.g., using toner or another suitable marking agent developed on a surface of the photoreceptor in accordance with the latent image.
Inaccurate positioning of the LED print head with respect to the surface of the photoreceptor can adversely impact how light from the LED print head is focused on the surface of the photoreceptor. In turn, an out of focus or poorly focused LED print head can adversely impact printing, e.g., it can introduce unwanted image artifacts.
One conventional approach to address accurate positioning of the LED print head with respect to the surface of the photoreceptor is to employ mechanical distance setting mechanisms, e.g., such a pins datuming and/or setting a spacing of the LED print head relative to the surface of the photoreceptor. However, in a dynamic xerographic print engine, such a solution may be insufficiently accurate and/or consistent or otherwise generally inadequate for some applications. For example, in some applications, it may be desired that a focused spot of light from an LED of the print head remains less than about 50 μm across on the surface of the photoreceptor, and generally it may be difficult and/or impractical to accurately and/or consistently achieve this degree of focus using such a pin datuming approach, e.g., due to variations in mechanical tolerances.
Accordingly, a new and/or improved method, system and/or apparatus is disclosed for automatically positioning and/or focusing a print head which addresses the above-referenced problem(s) and/or others.